View LUT?

[zaar]

I've seen on trello that VFB and color management is being worked on. So maybe this is in the works already.

I've would like to have a LUT in the VFB that doesn't get applied to the output, a "view LUT" if you will. More savvy people in the area of color management and color grading will probably have a better word for this an also want to use very specific view transform LUTs. I just want to preview my render with some extra punch, but then not have it burned in and then finesse it manually in Photoshop :)

[Aram Avetisyan]

Hi,

All the operators in Corona VFB can be toggled on or off. So, you can apply the LUT operator with the LUT of the choice, view it. And when exporting, the disabled it.
What is the issue or inconvenience with this method?

[zaar]

The inconvenience is that it's easily forgotten.
So just like modifiers have off in viewport I'd like "off in output" or a "display only LUT". But since Max has such huge troubles remembering to write my tiffs as 16-bit, I've started using CXR more, in which case this is not an issue since I can change it afterwards :D For animation however batching with corona image editor is something I've yet to try, it still can't edit mutiple files or a sequence right?

[TomG]

It can edit a sequence or batch using batch processing, so you can write for example a little script that will apply the same tone mapping or same lightmix to all images inside a folder and save them out to PNG, etc. What would be hard is animating those changes over a sequence :)

[zaar]

Yeah, that's a solution that's probably works for those who really need it and I don't think anyone has any want to animate the settings and basically have CIE become a video editor.

But "you can write a little script" isn't really aligned with my image of the Corona brand or philosphy of just making things kind of easy for the user (just speaking for myself here). Instead of a several users making little scripts that are basically the same. Maybe a developer can write a little bit* of code to be ably to apply a preset in CIE to a folder?

* I have no idea how little that bit of code is ;D

[piotrus3333]

Corona does have a view transform. you just can not change it or turn it off. 3dsmax gives you the option to apply it, not to apply it or even apply a different one when it asks you what gamma would you like to save your output with.

[maru]

The inconvenience is that it's easily forgotten.

Wouldn't it be the same inconvenience with a "view LUT"? You save your image, open it in another app, and then realize that it looks different, because the LUT was set to only be viewed, not saved.

[zaar]

haha, of course! :D You can't safegaurd 100% against other peoples ability to make errors.

But I would think this would be a more "pro" or advanced feature that only people that know what they do, would enable. You can hide it a bit if you want :)

Don't you get request likes this from animation or vfx people? I know it's not the main area of Corona, and maybe this is a more v-ray like advanced feature that fits in a more professional pipeline where you might want to view with one LUT and save out as "raw" to have it carefully color graded later.

[zaar]

Just noticed there's another LUT thread that I missed, and that there a bad mood in there. Sorry if I'm naggin about LUTs here, no harm meant.

[maru]

No worries, we are open to any suggestions. What I think we are missing in this thread (and also the other one) is why exactly the feature is wanted.

[zaar]

Maybe this is because I'm a photographer also, or because I'm just a coward that wants infinite flexibility. I'm not one of those who wants to have final image in the VFB. As final as possible is of course nice. And I want the ability to use a LUT when working to get a glipse of what a final polished result would be. But I find that LUTs sometimes push it too far, maybe blow highligts/shadows or have to much of style that I might want to back away from in post. Or maybe a little more flexibility to paint/mask in extra contrast in certain places, without having the LUT do it globally.

[piotrus3333]

Just noticed there's another LUT thread that I missed, and that there a bad mood in there. Sorry if I'm naggin about LUTs here, no harm meant.

it’s an important missing feature to nag about.
you have my vote.

+1

[pokoy]

No worries, we are open to any suggestions. What I think we are missing in this thread (and also the other one) is why exactly the feature is wanted.

3ds max has this feature built in since ages:
https://help.autodesk.com/view/3DSMAX/2022/ENU/?guid=GUID-556B3B1C-D62E-48F6-A633-DCF5172219B5
Though this is meant to work with LUTs created with other Autodesk compositing apps like Flint, Inferno etc.

Newer max versions have this, too, as part of the OCIO pipeline.

In a VFX house that takes its color pipeline seriously, the comp department may give you a LUT that you load in your 3d app and use *only for the display, not the saved file*. This way they ensure that your image output is as neutral as possible and will match their grading once your output is added to their footage.

A typical example from the world of printing is that you can enable a proof preview in Photoshop. You still work in RGB but the preview will display colors as they would look *after* conversion to CMYK and the specific CMYK profile used in PS settings.

I remember working on a plate shot on an Arri camera and there was just no time for a preliminary grading or the guys were busy with other stuff. Film cameras mostly have an absurdly flat image output if ungraded. It was super hard to get the same look in rendering which I was expected to deliver, it had to match the plate 1:1. With a LUT preview, the plate I was rendering against and the rendered output would've been previewed in what the comp guys were doing with it later, giving me a much better idea of what the final result would look like. Without it, I had a hard time to figure out whether my colors were too dark, too bright, too saturated etc.

I think the OP just asks for this for convenience so he can have a quick preview grading quality while making sure the file saved would still be 'untouched' and the final color adjustments would be done at a later stage.

+1 from me, it just widens your audience, maybe not for archviz but there are people who need this in some pipelines. If you ask me, Corona should take color management more seriously. Max was pretty late to the party but now has complete OCIO support and is improving it. As always, all users will benefit from a broader use of color management even if they don't understand why it's there or what it does.

15 years ago only a few people knew why gamma correction is important, it took a few years until Max defaulted to 2.2. Then it took another few years to implement Reinhard compression and now we're getting new better looking renders with improved tonemapping from filmic, ACES, Agx etc.

[maru]

Thanks Pokoy, that's an awesome explanation. If you would like to share any thoughts here, that would be super helpful as well: https://forum.corona-renderer.com/index.php?topic=40988.0

[James Vella]

I remember working on a plate shot on an Arri camera and there was just no time for a preliminary grading or the guys were busy with other stuff. Film cameras mostly have an absurdly flat image output if ungraded. It was super hard to get the same look in rendering which I was expected to deliver, it had to match the plate 1:1. With a LUT preview, the plate I was rendering against and the rendered output would've been previewed in what the comp guys were doing with it later, giving me a much better idea of what the final result would look like. Without it, I had a hard time to figure out whether my colors were too dark, too bright, too saturated etc.

I think the OP just asks for this for convenience so he can have a quick preview grading quality while making sure the file saved would still be 'untouched' and the final color adjustments would be done at a later stage.

+1 from me, it just widens your audience, maybe not for archviz but there are people who need this in some pipelines. If you ask me, Corona should take color management more seriously. Max was pretty late to the party but now has complete OCIO support and is improving it. As always, all users will benefit from a broader use of color management even if they don't understand why it's there or what it does.

15 years ago only a few people knew why gamma correction is important, it took a few years until Max defaulted to 2.2. Then it took another few years to implement Reinhard compression and now we're getting new better looking renders with improved tonemapping from filmic, ACES, Agx etc.

Isnt this contradictory? Why would you work in Reinhard when matching plates? Wouldnt it be easier to work in Linear instead? When you work with Reinhard the image is already tonemapped, thus you lose the proportional light intensity between the light and pixels. You can easily work in linear to to match apertures to physical behavior's of the camera instead of 'stacking' post production layers to suit.